Abstract: A bellows for a compensator as an elastic connection between two duct connection pieces or flange frames arranged from each other in the longitudinal direction is presented. The bellows contains a cavity arrangement between an outer wall, an inner wall, and curved sections at each end of the outer and inner walls. The outer wall, inner wall and curved sections are continuously connected. The cavity arrangement between the outer wall and the inner wall is designed as a single-chamber cavity. The single-chamber cavity between the outer wall and the inner wall is formed in a manner such that it is free from connecting webs. The material of the bellows is flexible.

Abstract: A flange connector for joining forced air duct sections together, consisting of angle bar members attached to the end edges of the duct sections, the cross-section of the angle bars feature parallel and perpendicular flanges that run parallel and perpendicular to the respective enclosing wall of the duct. The angle bar members are connected with corner fittings which feature two pin-like lugs situated perpendicular to each other.